asin(a - x)
-1 ----------------- ______________ / 2 \/ 1 - (a - x)
a - x ----------------- 3/2 / 2\ \1 - (a - x) /
/ 2 \ | 3*(a - x) | -|1 + ------------| | 2| \ 1 - (a - x) / -------------------- 3/2 / 2\ \1 - (a - x) /